Mode Definition and 324 Threads

Hi, The attenuation resulting from puting a signal into a parallel plate waveguide is dependent on the excited mode. Why does the TM mode have greater attenuation than the TE mode? I can see in the maths it 'works out' to be that, but what would be a more conceptual/physical reason? Is the...

It's given, "fibre optics are thin to accommodate single electromagnetic mode" what do they mean by single electromagnetic mode...? And also mentioned it has high bandwidth, i know that bandwidth is difference of highest and lowest frequencies of the signal. So if fibre optics has high...

Would it be possible? -- A fifth mode of transport... There has been a lot of talk about developing a fifth mode of transport, and most of these involve some sort of tube such as the hyperloop idea from Elon Musk. Now I don't know why but I have the idea stuck in my head that the fifth mode of...

In the following diff amp, only one output is taken from collector two. When I calculate the differential mode gain using the second differential input (-Vid/2) I get a positive gain. When I calculate the differential mode gain using the first differential input (Vid/2) I get a negative...

I am having trouble getting this. I have been introduced to common mode and differential mode signals. I assumed the inputs to a differential amplifier is an ac signal... my instructor gave instruction on how to input such a signal to a circuit using SPICE, he used DC. is the common mode dc...

Hi Why do we always bias a mosfet in Saturation mode? Is it becaus gm is more in saturation or is it because gm is more linear in saturation? Thanks Salil

Homework Statement A boost SMPS has the following design properties: Input Voltage - Vi = 6.0v Maximum Output Current - Io(max) = 0.5A switching frequency - F = 100khz Inductor = 500μH Capacitor = 1000μF with ESR 25mΩ Consider the boost SMPS operating in discontinuous conduction...

I read that bridge mode in amplifiers will, for example, take a 100 watt amplifier at 8ohms and turn it to a 200 watt amplifier at 4ohms. I was going to use 2 tda2050 amps, each running one speaker, but if I use 2 amps in bridge running 2 8ohm speakers in parallel, would this give me double...

http://arxiv.org/abs/1307.5830 but its from gravitational lensing not primordial gravity waves so guess we are still waiting for those, but a good sign methinks.

Too familiar with Bose Hubbard model, but suddenly got stuck by a simple question: Why is the kinetic term (to be precise should be single body part) negative?

Hello everyone, I am working on a coil design and have a question. The coil is meant to operate in continuous conduction mode, so the current waveform is a ramp waveform. B=V*t / N*Ae When calculating V*t do I use 1/2 t (since the current only increases for the first half of the...

Homework Statement Hey guys. The title says it all pretty much. We need to find the normal mode frequencies of a driven/forced system containing 3 equal masses connected by 4 springs of equal spring constant k. Homework Equations F=m\ddot{x} Spring potential V = 0.5kx^{2}...

Hi all, I am trying to mathematically proof that one can neglect convection and radiation when two cubes (paraffin-based, 1x1x1cm) are in direct contact on one side whilst the other 5 sides are perfectly insulated. Any ideas on how to calculate the Nusselt number here? How do you justify that...

What is an "Optical Mode". I've been reading a lot of solar cell articles, especially those having to do with nanophotonics. There is a term that I keep running into, 'optical mode', but I've yet to find an explanation that I can visualize or understand. What exactly is the "mode" being used...

Question about continuous conduction mode converter I have a few quesitons about CCM converters I have posted a basic schematic of the circuit in question as an attachment. The circuit is a series LC circuit in which the inductor and capacitor charge during the on time. During the off time...

Homework Statement The number 15 is added to each of the biggest 150 numbers in a distribution of 301 numbers in other words n=301 A. How does this addition affect the median of the distribution B. how does this addition affect the mode of the distribution C. How does this addition affect...

Question about the "register plus immediate" addressing mode Homework Statement The question: "Why does adding addressing modes like register plus immediate to an instruction set architecture tend to improve performance?" The answer: "Adding additional addressing modes to an instruction...

How do you characterize an antenna in receiving mode? The book said a LHC antenna in transmitting mode is RHC in receiving mode. Also if the antenna is LHC in transmitting mode, it's transmission characteristic is defined as \hat {E}_{(z,t)}=\frac{\hat {x}+\hat {y} j}{\sqrt{2}}. But the same...

I have a brand new HDMI cable that was successfully tested with another laptop but it doesn't work with mine. I tried everything but I only manage to get extended mode working which still doesn't have good resolution on my tv. On other resolutions it doesn't work and on duplicate mode none of...

I am looking for some comparison of feed thru caps, ferrite beads and common mode chokes. when to use which etc. Feed thru basically shunts noise to ground. But if the circuit ground to Earth is not so exactly low impedance, some of the noise will end up in the circuit. Isn't a common mode...

Can we simply understand a softened phonon mode as one having reduced energy/frequency? Does "soft" indicate smaller value of the spring coefficient like the k in f=kx, where f is force and x is displacement of a spring, so a "soft" spring has a smaller k value? Thanks...

Homework Statement Hi everyone! first post here :) Basically, the question is as follows: Consider a hydrogen fluoride molecule (atomic mass of H is 1g/mole and of F is 19 g/mole). 1. Write the energy of the system in terms of the displacements of both atoms. There are other questions...

hi in wave guide and transmission line i didn't understand what is the importance of TE11 mode ... any help !

EDIT: I have updated the original post to make my confusion more clear! Hello all, Attached below are the pages from my textbook for which I am concerned. On page 245 we can calculate the average inductor current as follows, I_{L} = \frac{1}{2}I_{max}(D+D_{1}) Now what I thought an...

i am beginner in transistors i can't understand common emitter configuration for saturation mode ,i am new in electronics and need help

Hello Everyone, I am working on DC-DC converters. The actual approach of my circuit is that to maintained the output voltage remains constant for both line and load regulation. So that, I added the feedback loop of my circuit from the load resistor. To maintained the constant output voltage...

Homework Statement The first vibrational band in the absorption spectrum of H2CO is at 28871 cm-1. The first two bands in the emission spectrum (from v'=0 level) lie at 27021 cm-1 and 24687 cm-1. Explain these observations. Determine the band origin of the electronic transition and the...

Hello, My question stems from a research project of mine involving taking the normal modes of clusters of molecules from a potential. I was curious of the interpretation that can be made of normal mode vectors at a non-equilibrium structure, i.e something following a MD trajectory beginning at...

Hello, My question stems from a research project of mine involving taking the normal modes of clusters of molecules from a potential. I was curious of the interpretation that can be made of normal mode vectors at a non-equilibrium structure, i.e something following a MD trajectory beginning at...

I have been wondering about the physical reason why a TE wave that goes STRAIGHT through the waveguide(without any reflections) can't propagate and would like some one to clarify the same OK..so if i consider a UNIFORM PLANE TE WAVE that goes straight thorough, then by definition of uniform...

Suppose a person takes data (say counts per minute of cars going past his window), for a long time. Then he loses his data, but knows that he counted 5 cars more often than any other number. What is the likely range for the average count rate? I tried to solve this by saying the mode is 5, so...

Can you calculate the frequency at which a bond vibrates when you know what frequencies of EM radiation it absorbs? Using carbon monoxide as an example. It has a stretching frequency at around 2100 cm-1. In electron volts, that would be around 0.3 eV. If I'm not mistaken, this is the energy it...

Hi, I've already made a question and recently received a reply. My question is how does a microcantilever have a torsional resonant mode. We generally study a longitudinal mode, not so much considering the torsional mode. The man who replied to my question said "It's because of...

Homework Statement Evaluate the ratio of the power contained within a circle of radius W(z) in the transverse plane to the total power in the Hermite-Gaussian beams of order (1,0) Homework Equations P=\intIdA The Attempt at a Solution I have determined the ratio for the Gaussian...

Hi, I am correcting a Embedded C code which requires Burst sleep mode. This sleep period is purely depend on the user input cool time and this is really to coll the machine. I thought of using Sleep function for this user input time but is it able to respond to other interrupts in this...

So the problem I am having is I have no idea what I am supposed to do. I read the chapter on spatial pattern in JD Murrays Math Bio Vol 2 and looked through Strogatz Nonlinear Dynamics and Chaos but I am not sure how to solve anything with these modes. I have no idea what to start doing. $$...

I'm working on an analysis problem using Abaqus. I would like to compare my results with an exact equation. My problem is modeled as a simply supported beam with a lumped mass at the end. The equation that I'm using for the exact solution is as follows: k=3EI/L3 ωn=\sqrt{k/(M + 0.23m)} How do...

I have never been able to grasp why certain mode shapes are the way they are. For example, I ran a free vibration analysis on a vertical beam fixed at the ground. The second mode shape is vertically straight. This is the same case whether or not I have a lumped mass at the top of the beam. Any...

I am doing an undergraduate project on bars and I am trying to derive the bar instability mode given by Mo et al. It says "whether or not a disk is globally stable depends on the global properties of the disk... it is not possible to write down a universal dispersion relation or stability...

Let's say a shielded cable is in the vicinity of noisy environment with plenty of EMI. How to go about cancelling the common mode currents, so that the magnetic field gets cancelled. It's pretty simple in case of differential mode currents. The mag field from the forward current and return...

I am a PHD student doing research on Ti:sapphire lasers so that when I enter the lab I have a full understanding of workings of the laser. I was wondering if anyone could go over the finer points of the mechanism of self mode locking in a Ti:sapphire laser? I have a picture in my head that...

This isn't a homework question in its entirety, I'm just wondering what the difference is between a Mode ratio and a mode shape? I'm taking a mechanical vibrations course and trying to figure out what the problem is asking for when it wants a mode shape...

Hi people, we were doing an experiment in lab where we excite a plate clamped at the circumference at various frequencies to detect natural frequencies. My questions are: 1. Sometimes at certain frequencies, we were observing multiple mode-shapes (an overlap of two mode shapes, to be exact)...

I am trying to determine the mode of operation for the following circuit and find the voltages and currents: I am given that β = 50 I know that VEC > VEC,sat for a transistor in active mode I applied KVL on the right loop and got: VCC = 300Ic + 1000Ic + VEC VEC = VCC - 1300Ic i'm...

As for transmission line(which operates on TEM mode), electric field is created by the opposite polarity of surface charge on both conductors, and magnetic field is by the electric current in both conductors. These two fields are perpendicular to each other, which makes "the" TEM mode. Then...

# of photons in a mode (in a blackbody) I've been going over a proof again concerning the thermal average number of photons in a mode of a cubical blackbody of length 'L' at equilibrium with a reservoir of temperature 'tau' (has a small hole in it, etc. etc. etc.) The logic went as usual...

Hi all, I have a doubt regarding saturation mode of BJT. Saturation occurs when both emitter-base junction and base-collector junction gets forward biased. For forward biasing a silicon p-n junction only 0.7V is needed. So is for emitter-base junction. But not for base-collector junction...

Hi, I'm trying to locate a formula for determining the radial breathing mode of a hollow cylinder. The dimensions of the cylinder of interest are approximately .5" OD x .4" ID x .5" L Any help would be greatly appreciated. Thanks!

I have been trying to figure out how to plot a differential equation using my TI Nspire with very little luck. I managed to find that I can set the graph of the calculator to a directional field but I am not 100% sure I am getting the right results. So I figured I would ask to see if anyone here...

Hi. In order to measure the I-V curve of a normal diode in pulsed mode, I set up the following experimental kit. The experimental results do not change with pulsewidth, which is quite long (us regime), and low frequency (200hz and less). An HP pulse generator is connected via BNC cable to an...